The present invention relates to a data communication control apparatus and its control method, an image processing apparatus and its method, and a data communication system which realize interactive video communication among a plurality of points.
A multipoint video conference system widely used now enables video conference terminals based on the ITU-T Recommendation H. 320 and the like to perform interactive communication among a number of points via a multipoint connection device.
As standards related to the multipoint connection device to control such multipoint connection among video conference terminals, the ITU-T Recommendation H. 231 defining the functional construction of the multipoint connection device and the format of multipoint communication, the ITU-T Recommendation H. 243 determining an in-channel communication procedure and the like have been made.
FIG. 1 shows the construction of a conventional video conference system. In FIG. 1, a multipoint connection device 22 interconnects video conference terminals 21a to 21n at three or more points, and performs audio mixing, video data delivery control or video data combining for split screen view, further, performs presidential control over the conference. In this manner, a multipoint conference connecting a plurality of remote points can be realized by connecting terminals via a multipoint connection device as long as the terminals are based on the Recommendation H. 320.
To realize multipoint interactive video communication in a video conference system based on the Recommendation H. 320, to deliver image data from the multipoint connection device 22 to the video conference terminals 21a to 21n as shown in FIG. 1, the following methods (1), (2) and the like have been put into practical use:
(1) A method to deliver a video image from a specific video conference terminal designated by a presidential terminal to the respective video conference terminals.
(2) As shown in FIG. 10, a method to reduce video images from respective video conference terminals 21a to 21n in the multipoint connection device 22, so as to simultaneously deliver images from respective video conference terminals 21a to 21n within a limited band.
Note that in FIG. 10, numerals 31a to 31d denote video data transmitted from the respective video conference terminals 21a to 21d; 32, reduced and synthesized video data delivered from the multipoint connection device 22 to the respective video conference terminals 21a to 21d. 
Further, to realize a video conference system in an Internet environment, software programs such as CU-SeeMe by White Pine Software, Inc. have been provided. In the multipoint video conference system, image data transmitted from the respective client terminals are delivered via a multipoint connection server to the respective client terminals without any processing. FIG. 11 shows video data transfer in this system. In FIG. 11, numerals 41a to 41c denote client terminals realized by personal computers or the like having video and audio input/output functions; 42, a multipoint connection server which delivers video and audio data from the respective client terminals 41a to 41c to the client terminals 41a to 41c without any processing.
However, the conventional video conference system using the multipoint connection based on the Recommendation H. 320 or the like, in which communication is performed within a limited band to the respective terminals, has problems as follows.
(1) Only the video image of a particular reference participant is delivered; or
(2) As reduced images of plurality of participants are transmitted, the images of the respective speakers are unclear.
In the video conference terminal, it is difficult to simultaneously and clearly display a plurality of conference participants.
Further, in the video conference system utilizing the Internet as shown in FIG. 11, the multipoint connection server 42 delivers video and audio data from the respective client terminals 41a to 41c to the client terminals 41a to 41c without any processing. For example, between the multipoint connection server 42 and the client terminal 41a, the client terminal 41a transmits terminal information A to the multipoint connection server 42, and the multipoint connection server 42 transfers terminal information B and C from other client terminals 41b and 41c to the client terminal 41a. Accordingly, the code amount of the image data delivered from the multipoint connection server 42 to the client terminals 41a to 41c increases in proportion to the number of conference participants (terminals). If a sufficient band is not ensured as a communication channel, the frame rate of images received by the client terminals 41a to 41c is extremely reduced. Accordingly, to display a received image, so-called frame thinning, i.e., omitting a frame at predetermined intervals, must be performed.
Accordingly, it is an object of the present invention to provide a data communication control apparatus and its control method and a data communication system which enable high-quality image communication. It is another object of the present invention to provide a data communication control apparatus and its control method and a data communication system which enables image communication without degration of the quality of the important portion of an image even if using a narrow band communication channel.
According to the present invention, the foregoing objects are attained by providing a data communication control apparatus comprising: compression means for compressing image data to be transmitted; communication means for transmitting the image data compressed by the compression means to the terminals; recognition means for recognizing a specific area in the image data; and compression control means for controlling a compression method in the compression means in accordance with whether or not an object area in the image data is the specific area.
It is another object of the present invention to provide a data communication control apparatus and its control method and a data communication system which enable clearly displayed facial expressions of participants in a multipoint video conference system.
According to the present invention, the foregoing object is attained by providing the data communication control apparatus wherein the specific area is an area showing a person""s face.
It is further object of the present invention to provide an image processing apparatus and its method which mitigate degradation of image quality upon reuse of compressed image data.
According to the present invention, the foregoing object is attained by providing an image processing apparatus comprising: recognition means for recognizing a specific area in an image represented by compressed image data; and compression control means for controlling a re-compression method for re-compressing the compressed image data based on recognition by the recognition means.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same name or similar parts throughout the figures thereof.